The present invention relates to a battery-powdered mobile communications apparatus and, more particularly, to a battery-powered mobile communications apparatus having a function to reset its transmitter when the output of the battery falls below a prescribed level.
Mobile communications apparatuses, particularly battery-powered ones, have a transmitter reset function because, when the battery output falls below a prescribed level, the transmitter is susceptible to such abnormalities as output interruption or radiation of radio waves at unlicensed frequencies. This reset function monitors the output level of the battery, and turns off the transmitter when the output falls below the prescribed level.
Since the transmitter consumes much power, as the battery deteriorates, its output level steeply falls off transiently when the transmitter is turned on, and the reset function is actuated to turn off the transmitter. But, once the transmitter is turned off, the output level of the battery is restored relatively quickly. This restoration releases the reset function, and further an instantaneous drop detector circuit in the apparatus judges the transient fall of the battery's output level as an instantaneous drop. The transmitter is again turned on in response to the release of the reset function and to the judgement of instantaneous drop detector circuit.
The reactuation of the transmitter invites a steep fall of the battery's output level again, and the aforementioned process is repeated. As a result, the transmitter is turned on and off repeatedly, making normal communication impossible.